Construction of motorized wheel for vehicle motorization

ABSTRACT

A motorization apparatus for a motorized wheel comprises an axle secured to a frame of a vehicle. A rotor unit has poles of magnet material. A stator unit having slots and teeth secured to the axle is inward of said rotor to define a clearance gap therewith such that the rotor unit is rotatable about the stator core. An arrangement of coils is wound around the teeth of the stator unit, the coils adapted to be powered to induce a rotation of the rotor unit relative to the stator unit. A structure comprises hub portions rotatably mounted to the axle, the structure having lateral walls defining an inner volume for the rotor unit and the stator unit, the structure supporting the rotor unit. The structure comprises attachment members connected to spokes of the motorized wheel, located radially inward of the clearance gap between the rotor unit and the stator unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority on U.S. Provisional ApplicationSer. No. 61/819,896, filed on May 6, 2013, and on U.S. ProvisionalApplication Ser. No. 61/824,139, filed on May 16, 2013.

TECHNICAL FIELD

The present application pertains to a construction of a wheel featuringa wheel motor, a.k.a., motorized wheel, wheel hub drive, wheel hubmotor, hub motor, in-wheel motor, etc, for vehicle motorization.

BACKGROUND OF THE ART

Wheel motors are commonly used for the motorization of vehicles, such asbicycles, scooters, lightweight motorcycles, cars, etc. A wheel motorcomprises a stator hub with windings, and a rotor wheel rotating aboutthe hub. The rotor wheel comprises a plurality of magnets driven by thecurrent in the windings. Advantageously, the wheel motor operates as adirect drive; there is no transmission to convert the motor output to agiven speed. The power output of the wheel motor is as a function of theelectrical current fed to the wheel motor.

There are continuous efforts to increase the power output from wheelmotors. Some parameters can be used to alter the power output of thewheel motors, such as rotor size. However, there may be constraints toadjusting a rotor size, as wheels come in standard dimensions. Forinstance, bicycle wheels for adult bicycles typically come withinstandard diameters, such as 26 inches, 29 inches, 700 mm or 650 mm. Inorder to maximize the size of the motors, spokes are conventionallyattached to an outer periphery of the motor casings, with substantiallyshorter spokes than usual for standard-diameter wheels. As spoke add tothe comfort of the rider for instance by their flexing action, theshortening of the spokes may have an adverse effect on the ridingexperience.

SUMMARY

It is therefore an aim of the present disclosure to provide aconstruction of a wheel and wheel motor that addresses issues associatedwith the prior art.

Therefore, in accordance with the present disclosure, there is provideda motorization apparatus for a motorized wheel comprising: an axleadapted to be secured to a frame of a vehicle; a rotor unit having aplurality of poles of magnet material; a stator unit secured to the axleand being inward of said rotor and defining a clearance gap with therotor unit such that the rotor unit is rotatable about the stator core,said stator unit having slots and defining teeth between said slots; anarrangement of coils of insulated wire being wound around the teeth ofthe stator unit, the coils adapted to be powered to induce a rotation ofthe rotor unit relative to the stator unit; a structure comprising hubportions rotatably mounted to the axle, the structure having lateralwalls defining an inner volume for the rotor unit and the stator unit,the structure supporting the rotor unit relative to the stator unit forthe rotor unit to rotate with the structure about the stator unit, thestructure further comprising attachment members adapted to be connectedto spokes of the motorized wheel, the attachment members being locatedradially inward of the clearance gap between the rotor unit and thestator unit.

Further in accordance with the embodiment, the hub portions are onopposite sides of the motorization apparatus and each have: a tubularportion; and at least one bearing per tubular portion connecting thetubular portion to the axle for rotation of the tubular portion relativeto the axle.

Still further in accordance with the embodiment, each of the hubportions has a flange projecting radially from the tubular portion, theattachment members being on the flange.

Still further in accordance with the embodiment, the flange has acrenellated periphery and the attachment members are holes in thecrenellated periphery.

Still further in accordance with the embodiment, the attachment membersare on a diameter of the flange ranging between 20 and 500 mm.

Still further in accordance with the embodiment, the structure comprisescover plates connected to the hub portions, the cover plates extendingradially from the hub portions and interconnected to one another at anouter periphery of the motorization apparatus, the cover plates definingconcurrently a substantial portion of the inner volume enclosing therotor unit and the stator unit.

Still further in accordance with the embodiment, the cover plates aremade of a non-ferrous material.

Still further in accordance with the embodiment, at least the tubularportions of the hub portions are made of metal.

Still further in accordance with the embodiment, one of the hub portionsfurther comprises one of a freehub and a freewheel hub having a firstend connected to and rotating with the tubular body, and a secondcantilevered end projecting away from the hub portion.

Still further in accordance with the embodiment, at least one channel isdefined in an outer surface of the shaft for routing at least one cablefor powering or controlling a power to the arrangement of coils, a firstend of the at least one channel communicating with the inner volume ofthe structure, and a second end of the at least one channel beingexterior to the structure.

Still further in accordance with the embodiment, a dropout abutment onthe axle is adapted to prevent rotation of the axle relative to theframe of the vehicle.

Still further in accordance with the embodiment, a printed circuit board(PCB) is secured to the stator unit and wired to the arrangement ofcoils.

Still further in accordance with the embodiment, at least one receptacleis fixedly secured to the stator unit and positioned in one of theslots, the at least one receptacle adapted to receive therein a sensorof the PCB to determine an orientation of the rotor unit relative to thestator unit.

Still further in accordance with the embodiment, the stator unitcomprises eighty-four of the slots.

Still further in accordance with the embodiment, the eighty-four slotsare regrouped in four continuous sets of teeth per phase.

Still further in accordance with the embodiment, each of the continuoussets of teeth per phase has seven teeth.

Still further in accordance with the embodiment, there are one ofeighty, eighty-eight and ninety-two of the poles.

Still further in accordance with the embodiment, one of splineconnection, knurling, serrated splines is between the axle and thestator unit.

Still further in accordance with the embodiment, a ratio of rotor radiusto rotor width of at least 10.

Still further in accordance with the embodiment, there is provided amotorized wheel comprising: the motorization apparatus according to theabove; a rim; and spokes extending from the rim to the hub portions ofthe structure, a wheel inner volume being bound by innermost ones of thespokes, with at least the rotor unit being within the wheel innervolume.

Still further in accordance with the embodiment, the arrangement ofcoils of insulated wire being wound around the teeth of the stator unitis within the wheel inner volume.

Still further in accordance with the embodiment, the rim has a diameterbetween 584 mm and 700 mm.

In accordance with a further embodiment of the present disclosure, thereis provided a motorization apparatus comprising an outer rotor witheighty, eighty-eight or ninety-two poles constructed with segments ofpermanent magnet material sequentially magnetized north and south, theouter rotor adapted to be part of a wheel and rotating with the wheelabout an axis thereof; a stator core of ferromagnetic material spacedinwardly of said rotor and defining a clearance gap with the rotor suchthat the rotor is rotatable about the stator core, the stator corehaving an outer diameter ranging between 150 mm and 500 mm, said statorcore having eighty-four slots and defining teeth between said slots; anda three-phase winding with coils of insulated wire being wound aroundthe teeth of the stator core.

Still further in accordance with the further embodiment, the outer rotorhas eighty-eight poles, and wherein the three-phase winding is dividedin four sets of consecutive teeth for each of the three phases

Still further in accordance with the further embodiment, each of thefour sets of a same phase has two pairs of sets that are diametricallyopposed in the stator core.

Still further in accordance with the further embodiment, the three-phasewinding are divided into four sets of seven consecutive teeth for eachof the three phases.

Still further in accordance with the further embodiment, each said phaseof the three-phase winding is divided into sets of six and eightconsecutive teeth.

Still further in accordance with the further embodiment, the stator isfixed to an axle of the wheel.

Still further in accordance with the further embodiment, the rotor isadapted to be operatively connected to a freewheel or freewheel hub of avehicle to rotate therewith in one rotational orientation.

Still further in accordance with the further embodiment, each said phasecomprises 28 teeth.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a motorized wheel in accordance with thepresent disclosure;

FIG. 2 is an enlarged perspective view of a driven-side or brake-sidehub shell of the motorized wheel of FIG. 1;

FIG. 3 is a sectional view of the motorized wheel of FIG. 1;

FIG. 4 is an enlarged sectional view of the motorized wheel as in FIG.3, showing a hub thereof;

FIG. 5 is an enlarged perspective view of the hub of the motorized wheelof FIG. 1;

FIG. 6 is an enlarged sectional view of the motorized wheel as in FIG.3, showing a rotor unit and a stator unit;

FIG. 7 is an enlarged perspective view of FIG. 6;

FIG. 8 is a schematic diagram of an exemplary rotor and stator of themotorized wheel of FIG. 1;

FIG. 9 is an enlarged view of a receptacle for receiving a sensor aspositioned in a slot of the stator unit of motorized wheel of FIG. 1;and

FIG. 10 is an enlarged view of an exemplary embodiment of an axle ofmotorized wheel of FIG. 1, in accordance with another embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings and more specifically to FIGS. 1 and 2, awheel with wheel motor in accordance with the present disclosure isgenerally shown at 10. The motorized wheel 10 is of the type that isused in vehicles such as bicycles, tricycles, scooters and any otherappropriate type of vehicle. The motorized wheel 10 is shown in aconfiguration particularly well suited to be used in a bicycle, notablyby the diameter and width of the motorized wheel 10. For example, themotorized wheel 10 is essentially similar to a back wheel of an adultsize bicycle, such as a 700 mm wheel, a 650 mm wheel, a 26 inch wheel, a29 inch wheel, (i.e., ISO5775, ISO 622 (700C and 29po), ISO 584 (650B),ISO 559 (26po)—range of 584 to 700 mm in diameter) despite the fact thatwheels of smaller or larger diameters could be used as well. Moreover,although the motorized wheel 10 is shown as having a freehub or afreewheel hub for supporting a cassette of cogs or freewheel, asdiscussed hereinafter, the motorized wheel 10 could be without such afreewheel hub. As an example, the motorized wheel 10 could be used asthe front wheel of a bicycle, which does not require a freewheel hub.

The motorized wheel 10 has a motorization apparatus featuring asynchronous machine 12. The synchronous machine 12 may also be referredto as a motor, a synchronous motor, an electric motor among other names.The synchronous machine 12 is configured to act as the hub of themotorized wheel 10 and is therefore connected to rim 13 by way of spokes14, so as to transmit its output to the rim 13. It is observed that, insimilar fashion to typical wheels, the spokes 14 define an inner volumeA between innermost ones of the spokes 14 on either side of themotorized wheel 10, as best seen in FIG. 3. The inner volume A is boundby the rim 13 and by the spokes 14.

The synchronous machine 12 is substantially lodged into the inner volumeA, and also serves as connection for ends of the spokes 14, in similarfashion to a hub. More specifically, as shown hereinafter, at least someof the active components of the machine 12 are in the inner volume A,including the rotor, magnets, stator coils, and/or stator, etc. An axle15 will interface the synchronous machine 12 and thus the motorizedwheel 10 to a frame component of the vehicle, for instance chain stays,a fork of a bicycle, or any other frame component, depending on the typeof vehicle with which the motorized wheel 10 is used. The axle 15 has agiven geometry that will be discussed hereinafter, but has endsextending beyond the synchronous machine 12, at which ends nuts 16 areprovided along with spacers 17 of different shapes for the motorizedwheel 10 to be releasably secured to a frame of the vehicle, forinstance in the drop outs thereof. Although not shown, the axle, nutsand spacers may for instance be part of a quick release skewer. The axle15 may also define an inner channel 18 by which wires may be introducedinto the synchronous machine 12 to provide power to the synchronousmachine 12 as well as commands.

Referring concurrently to FIGS. 3, 4 and 5, the synchronous machine 12is shown in greater detail as having a structure rotatably mounted tothe axle, the structure comprising a drive side hub shell 20, a drivenside hub shell 30, a drive side cover 40, a driven side cover 50. Thespokes 14 are connected to the structure as described hereinafter forconcurrent rotation. In FIGS. 5 to 7, a rotor unit 60 and a stator unit70 are shown being located in an inner volume B of the structure,substantially defined by the covers 40 and 50 of the synchronous machine12.

The drive side hub shell 20 is the component of the structure by whichthe synchronous machine 12 is rotatably mounted to the axle 15.

The driven side hub shell 30 is the component of the structure by whichthe synchronous machine 12 is rotatably mounted to the axle 15 on thedriven side of the vehicle or the brake side in a configuration of thewheel 10 with a disc brake. In an embodiment of the motorized wheel 10used without a freehub, there is no drive or driven side, whereby thehub shells 20 and 30 may be mirror images of one another. The hub shells20 and 30 concurrently form the hub of the wheel 10.

The drive side cover 40 and the driven side cover 50 concurrently formthe inner volume B of the synchronous machine 12 and will thereforeconcurrently house the rotor unit 60 and the stator unit 70, i.e., theactive components of the synchronous machine 12.

The rotor unit 60 is fixably secured to the covers 40 and 50 and willprovide rotational forces thereto, which rotational forces are sustainedby the rotor unit 60 by the powering of the stator unit 70.

The stator unit 70 is fixed to the axle 15 for instance by way of splinearrangement, knurling, serrated spline, etc and therefore does notrotate with the rotor unit 60. The stator unit 70 provides drivingforces that will induce a rotation of the rotor unit 60.

Referring concurrently to FIGS. 3 and 4, the drive side hub shell 20 isshown in greater detail. The drive side hub shell 20 has a tubularportion 21. The tubular portion 21 is generally coaxial with the axle15. A freehub 22 is connected to the tubular portion 21, and bearings 23rotatably support the tubular portion 21 about the axle 15. A pair ofthe bearings 23 are at an inside end of the tubular portion 21 andfreehub 22, whereas a seal 23A is at the outer end of the freehub 22(although a third bearing could be used instead of the seal 23A). As isknown in the art, the freehub 22 rotates concurrently with the tubularportion 21 in one direction. By using a seal 23A instead of a bearing,the end of the freehub 22 is cantilevered and, as such, is particularlywell suited to receive thereon strain gauges to measure the chaintension on the freehub 22 to calculate the pedalling power. In the otherdirection, a ratchet mechanism included in the freehub 22 will allow thefreehub 22 to remain stationary while the tubular portion 21 (and thusthe drive side hub shell 20) rotates. The freehub 22 may be a standardfreehub. It is pointed out that, as an alternative to a freehub 22, afreewheel hub could be provided as well. Moreover, although not shown,it is contemplated to use an internal gear mechanism with thesynchronous machine 12.

A radial flange 24 projects radially from the tubular portion 21. Theradial flange 24 may have a crenellated periphery defining a pluralityof spoke supports 25 by which ends of the spokes 14 will be connected tothe drive side hub shell 20. Throughbores or holes 26 are thereforeprovided on the spoke supports 25 to receive the ends of the spokes 14.The holes 26 in the spoke supports 25 are one of multiple attachmentmembers that may be used to connect spokes 14 to the structure, withother attachment members including tapped bores, nipples, etc. It isalso considered to connect the spokes 14 directly to the tubular portion21, with appropriate attachment members being provided in the tubularportion 21.

Referring to FIGS. 1 and 2, one contemplated wheel construction is shownwith a given number of straight pull spokes. However, any otherappropriate spoke arrangement is considered (e.g., hook spokes, etc). Itis considered to use spokes of standard size and construction forconvenience and ease of repair.

The drive side hub shell 20 defines a shoulder 27 of generally circularshape, upon which the drive side cover 40 will be abutted when thesynchronous machine 12 is assembled. Fasteners such as bolts, screwingengagement, and/or adhesives, etc may be used to secure the cover 40 tothe shell 20. Other connection arrangements are also considered for thejunction of the cover 40 to the shell 20.

The driven side hub shell 30 is generally speaking a mirror image of thedrive side hub shell 20, with the exception of the freehub 22, absentfrom the driven side hub shell 30, and with additional differences isgeneral shapes, for example. Hence, the driven side hub shell 30 has atubular portion 31 rotatably mounted to the axle 15 by bearings 33. Aradial flange 34 with crenellated periphery for example projects fromthe tubular portion 31 and has spoke supports 35 by which the drivenside hub shell 30 is connected to spokes 14. Throughbores 36 in thespoke support 35 will receive the ends of the spokes 14 (as one ofnumerous possible attachment members considered to connect the spokes 14to the structure). A shoulder 37 is oriented toward the inner volume Band serves as an abutment for the driven side cover 50, although otherconnection arrangements are considered for the junction of the cover 50to the shell 30.

Referring concurrently to FIGS. 5, 6 and 7, the drive side cover 40 isshown having a cover plate 41. A connector rim 42 is at an outerperiphery of the cover plate 41 and will serve to connect the drive sidecover 40 to the driven side cover 50. Driven side cover 50 also has acover plate 51 and has a complementary connector rim 52 that willcooperate with the connector rim 42 in the manner shown in FIG. 6 toform the casing of the synchronous machine 12. Referring to FIG. 1, thecover plates 41 and 51 and the connector rims 42 and 52 are respectivelyfastened to the hub shells 20 and 30, and to one another by way offasteners such as bolts, appropriate washers, bolts/screws and tapping,press-fitting, etc. It is shown that the covers 40 and 50 concurrentlydefine an inner volume B. Moreover, the combined geometry of the covers40 and 50 tapers in a radial direction, whereby a casing concurrentlyformed by the covers 40 and 50 fits inside the inner volume A defined bythe spokes 14, as observed in FIG. 3. In any event, the structure haslateral walls, for instance as defined partially by the covers 40 and50, which may or may not close the inner volume B.

Referring to FIG. 1, the covers 40 and 50 are shown having a generallyoctagonal outline, although other shapes may be used, such as circular,pentagonal, hexagonal, among numerous other possibilities. In order tooptimize the performance of the motorized wheel 10, the covers 40 and 50must be as light as possible, yet be capable of sustaining the stressesassociated with a motorized wheel. For instance, the covers 40 and 50may be in a non-ferrous material such as a composite material while thehub shells 20 and 30 are made of ferrous material or a metal, as the hubshells 20 and 30 are connected to the spokes 14. In selecting thematerials, the coefficients of thermal expansion should be taken intoconsideration, so as not to impede the rotation of the rotor unit 60relative to the stator unit 70. Moreover, although the hub shells 20 and30 are shown as being separate from the covers 40 and 50, the structurecould consist of the two half members, each half member being anintegral assemble of hub shell (e.g., 20 or 30) and cover (e.g., 40 and50). In such a case, the structure would have a hub portion integratedwith a cover. Other arrangements are considered as well.

As shown in the embodiment of FIGS. 3 and 4, the cover plates 41 and 51may be relatively thin, but with reinforcement ribs thereon. Due to thelimited space within the inner volume A, there is limited space for theribs on the outer surfaces of the cover plates 41 and 51. In theembodiment of FIG. 1, ribs are shown having different segments 53 and54. The segments 53 each extend along a first one of the spokes 14, andwhen a second one of the spokes 14 crosses over the first spoke 14, thesegments 53 end and the segments 54 commence, with the segments 54extending along the second one of the spokes 14. Hence, each rib has apair of segments 53, 54, to follow a pattern of the spokes 14. Althoughnot visible, the cover 40 may have a similar pattern of ribs.

Referring concurrently to FIGS. 6, 7 and 8, the rotor unit 60 is shownas having an annular body 61. The annular body 61 serves as a supportfor magnets 62. The magnets 62 are typically made of a ferro-magneticmaterial and may be of any appropriate shape, such as rectangular shape.Any appropriate number of magnets could be used as a function of theconfiguration of the stator unit 70.

Still referring to FIGS. 6, 7 and 8, the stator unit 70 is shown ashaving a stator support 71 by which the stator unit 70 is fixedlysecured to the axle 15. A yoke 72 is located on a circumferentialsurface of the stator support 71 and is configured to define a pluralityof teeth 75, with windings 73 thereon. The stator support 71 may beconfigured to support a printed circuit board 74 that will communicatewith the control by wires passing through the channel 18 of the axle 15,to control current circulation in the windings 73.

Any appropriate number of teeth for magnets is considered. For instancein FIG. 8, there is illustrated the yoke of the stator support 71 ashaving eighty-four slots, separated by teeth 75, typically made of iron(i.e., ferromagnetic material). Although not shown in FIG. 8 (but showin FIG. 6), the coils of insulated wire are wound about at least some ofthe teeth 75, in accordance with a phase interconnection describedbelow.

The rotor unit 60 is mounted about the stator unit 70, and is separatedfrom the stator unit 70 by a suitable clearance gap. In FIG. 1, there isillustrated eighty-eight of the permanent magnets 62, although eighty orninety-two magnets may be used as well with the eighty-four slots of thestator unit 70. Due to the large diameter of the machine 10 (andresulting lever arm effect), the magnets 62 may be significantly reducedin size as compared to standard machines. Hence, the high number ofpoles reduces the iron volume. By increasing the number of poles, theflux per pole during operation is reduced as compared with a machineproducing a similar power output with a lesser amount of poles.Accordingly, as the sectional dimensions of teeth are proportional tothe flux, the sectional dimensions for a eighty-four slot machine aresmaller than the sectional dimensions for the teeth of a machine withfewer slots, for a similar power output. There results a lower weightfor the eighty-four slot machine when compared to machines having afewer amount of poles for a similar power output.

The configuration of eighty-four slots allows some form of repeatabilityin the phase structure. The repeatability is well suited to balanceradial forces on the axle, thereby reducing the subharmonics which maycause vibrations. An example of a phase interconnection of the machine12 is shown, for the embodiment with eighty-eight magnets 62 for theeighty-four slots. The teeth 75 are regrouped in four continuous sets ofteeth per phase, as shown by sets A, B, and C. According to oneembodiment, each set comprises seven consecutive teeth 75. However,other arrangements of sets may also be used, for instance phases eachconsisting of a set of six and a set of eight consecutive teeth 75. Itis also considered to have other phase configurations, for instance withfour sets of six consecutive teeth 75, four sets of seven consecutiveteeth 75, and four sets of eight consecutive teeth 75, as an example.Any appropriate number of consecutive teeth per set for a total of sixsets may be used. By the arrangement of six sets of teeth with two setsper phase, it is observed that the four sets of a same phase arediametrically opposed in the stator unit 70, as shown by lines A-A, B-B,and C-C. In the embodiment featuring seven consecutive teeth per set,the centers of the sets of a same phase are diametrically opposed.Accordingly, the magnetic forces to which are exposed the sets of teeth75 operated in a same phase oppose each other and minimize their effecton the center of the stator unit 70. With the 3-phase interconnectiondescribed above, the above-referred phase interconnections andcomponents of the system of FIG. 8 may be off-the-shelf products.

In the embodiments of eighty-four slots and ninety-two magnets, theperiodicity of the back EMF sinusoidal signal generated by the magnet is2, so the teeth 75 are separated in two sets for each phase.

Although only shown schematically, the stator unit 70 has coils ofinsulated wire wound on the teeth 75. There are two coils per slot,although other suitable configurations may be used as well in themachine 12. Adjacent coils of a same set are typically wound in oppositedirections.

The interconnection of phases and the coil winding may be any otherappropriate alternative. For instance, there may be used a single coilper slot.

The 84-slot arrangement is relatively lightweight compared to machineswith similar power output but with fewer poles, notably because of thesubstantial reduction of size of the magnets 62. The 84-slot arrangementon the other hand has greater diameter than machines with fewer poles,whereby the resulting machine is well suited to be wheel-mounted, asbicycle wheels commonly have large diameters, for instance between 584mm and 700 mm (e.g., ISO5775: ISO 622 (700C and 29po), ISO 584 (650B),ISO 559 (26po)). Even more specifically, the 84-slot arrangement isrelatively narrower compared to machines with similar power output butwith fewer poles, resulting in a machine that is well suited to bemounted in between regular spoke patterns of a bicycle, not affectingthe ride comfort of the bicycle. In the direct-drive configuration on abicycle, the rotor may be operatively connected to a freehub asmentioned and illustrated in FIGS. 1-7, such that pedaling actuation istransmitted to the rotor via the cassette on the freewheel. On the otherhand, in the absence of a pedaling input, the freehub 22 allows idlingof the cassette while the machine 12 may actuate the wheel. As analternative, the direct-drive configuration may be used for the frontwheel of a bicycle.

Referring to FIG. 9, there is illustrated an arrangement to ensure theprecise positioning of sensors between the teeth 75 of the stator unit70. A receptacle 76 is fixedly lodged between the teeth 75, thereceptacle 76 being sized to accommodate a Hall effect sensor 77 orequivalent. The sensor 77 (a few of which are used but only one shown inFIG. 9) is connected to the printed circuit board 74, for instance byway of a flexible strip 78 (e.g., copper strips). Hence, the receptacle76 is structurally connected to the teeth 75, and the sensor 77 maysimply be inserted in the receptacle 76 to be aligned with the rotorunit 60 to measure the orientation of the rotor unit 60 relative to thestator unit 70.

Hence, the structure of the machine 12 has a geometry sized and shapedto fit in the inner volume A defined by the spokes 14. Conventionalspoke arrangements can thus be used for the motorized wheel 10, withstandard-size spokes. The use of such standard-size long spokes mayresult in a more effective wheel construction (in terms of mass,strength, assembly and/or comfort) than wheels in which short spokesextend from the circumference of the motor to the rim of the wheel. Thisspecific arrangement of machine 12 serving as a hub for the wheel 10allows the use of a large diameter motor, with the sturdy constructionof long spoke wheels. For instance, the arrangement show in the figuresmay have a ratio of maximum rotor radius to maximum rotor width of atleast 10. The spokes 14 may connect to the structure of the machine 12at a connection diameter ranging between 20 and 500 mm

Referring to FIG. 10, an alternative embodiment of the axle 15 is shown,in which channels 90 are defined in the outer surface of the axle 15.The channels 90 represent a suitable configuration for wires 91 of theelectronic components of the active components of the machine 12 to berouted out of the machine 12 to be connected to a battery and to a userinterface, as commonly known and used for such machines. Theconfiguration of FIG. 10 may increase the strength of the axle 15 andimprove its waterproofness. An abutment 92 is also visible in FIG. 10,the abutment 92 cooperating with the walls of the dropouts to preventrotation of the stator unit 70 relative to the frame of vehicle.

1. A motorization apparatus for a motorized wheel comprising: an axleadapted to be secured to a frame of a vehicle; a rotor unit having aplurality of poles of magnet material; a stator unit secured to the axleand being inward of said rotor and defining a clearance gap with therotor unit such that the rotor unit is rotatable about the stator core,said stator unit having slots and defining teeth between said slots; anarrangement of coils of insulated wire being wound around the teeth ofthe stator unit, the coils adapted to be powered to induce a rotation ofthe rotor unit relative to the stator unit; a structure comprising hubportions rotatably mounted to the axle, the structure having lateralwalls defining an inner volume for the rotor unit and the stator unit,the structure supporting the rotor unit relative to the stator unit forthe rotor unit to rotate with the structure about the stator unit, thestructure further comprising attachment members adapted to be connectedto spokes of the motorized wheel, the attachment members being locatedradially inward of the clearance gap between the rotor unit and thestator unit.
 2. The motorization apparatus according to claim 1, whereinthe hub portions are on opposite sides of the motorization apparatus andeach have: a tubular portion; at least one bearing per tubular portionconnecting the tubular portion to the axle for rotation of the tubularportion relative to the axle.
 3. The motorization apparatus according toclaim 2, wherein each of the hub portions has a flange projectingradially from the tubular portion, the attachment members being on theflange.
 4. The motorization apparatus according to claim 3, wherein theflange has a crenellated periphery and the attachment members are holesin the crenellated periphery.
 5. The motorization apparatus according toclaim 3, wherein the attachment members are on a diameter of the flangeranging between 20 and 500 mm.
 6. The motorization apparatus accordingto claim 2, wherein the structure comprises cover plates connected tothe hub portions, the cover plates extending radially from the hubportions and interconnected to one another at an outer periphery of themotorization apparatus, the cover plates defining concurrently asubstantial portion of the inner volume enclosing the rotor unit and thestator unit.
 7. The motorization apparatus according to claim 6, whereinthe cover plates are made of a non-ferrous material.
 8. The motorizationapparatus according to claim 7, wherein at least the tubular portions ofthe hub portions are made of metal.
 9. The motorization apparatusaccording to claim 2, wherein one of the hub portions further comprisesone of a freehub and a freewheel hub having a first end connected to androtating with the tubular body, and a second cantilevered end projectingaway from the hub portion.
 10. The motorization apparatus according toclaim 1, wherein at least one channel is defined in an outer surface ofthe shaft for routing at least one cable for powering or controlling apower to the arrangement of coils, a first end of the at least onechannel communicating with the inner volume of the structure, and asecond end of the at least one channel being exterior to the structure.11. The motorization apparatus according to claim 1, further comprisinga dropout abutment on the axle adapted to prevent rotation of the axlerelative to the frame of the vehicle.
 12. The motorization apparatusaccording to claim 1, further comprising a printed circuit board (PCB)secured to the stator unit and wired to the arrangement of coils. 13.The motorization apparatus according to claim 12, further comprising atleast one receptacle fixedly secured to the stator unit and positionedin one of the slots, the at least one receptacle adapted to receivetherein a sensor of the PCB to determine an orientation of the rotorunit relative to the stator unit.
 14. The motorization apparatusaccording to claim 1, wherein the stator unit comprises eighty-four ofthe slots.
 15. The motorization apparatus according to claim 14, whereinthe eighty-four slots are regrouped in four continuous sets of teeth perphase.
 16. The motorization apparatus according to claim 15, whereineach of the continuous sets of teeth per phase has seven teeth.
 17. Themotorization apparatus according to claim 14, comprising one of eighty,eighty-eight and ninety-two of the poles.
 18. The motorization apparatusaccording to claim 1, further comprising one of spline connection,knurling, serrated splines between the axle and the stator unit.
 19. Themotorization apparatus according to claim 1, further comprising a ratioof rotor radius to rotor width of at least
 10. 20. A motorized wheelcomprising: the motorization apparatus according to claim 1; a rim; andspokes extending from the rim to the hub portions of the structure, awheel inner volume being bound by innermost ones of the spokes, with atleast the rotor unit being within the wheel inner volume.
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